Throughout the world, glaciers are on the retreat. Within just a few decades, some that used to flow kilometers down the side of mountains have been reduced to vanishing remnants near summits. And not just in polar regions. The glaciers that long capped peaks within alpine reaches at tropical latitudes — such as in Peru and East Africa — are also drying up, and at a double-time pace.

Most news accounts have focused on these retreats as an early symptom of global warming — and make no mistak...